AT43USB353M_04 Datasheet, PDF (54/95 Pages) ATMEL Corporation – Low Cost Full-speed USB Microcontroller with Embedded Hub, ADC and PWM

ADC Characteristics
I/O-Ports
Port A
Symbol
Parameter
Resolution
Integral Non-linearity
Differential Non-linearity
Zero Error (Offset)
Full Scale Error
V_REF input resistance
Analog Input Resistance
Conversion Time
Clock Frequency
Condition
Min
Typ
10
V_REF = VCEXTA
V_REF = VCEXTA
-2
-4
25°C
12
18
100
12
at 50% duty cycle
Max Units
Bits
4
LSB
4
LSB
2
LSB
4
LSB
24
kΩ
MΩ
768
µs
1
MHz
All AVR ports have true Read-Modify-Write functionality when used as general digital I/O
ports. This means that the direction of one port pin can be changed without unintentionally
changing the direction of any other pin with the SBI and CBI instructions. The same applies for
changing drive value if configured as output or enabling/disabling of pull-up resistors if config-
ured as input.
Port A is an 8-bit bi-directional I/O port. The Port A output buffers can sink or source 2 mA.
Three I/O memory address locations are allocated for the Port A, one each for the Data Regis-
ter PORTA, $1B($3B), Data Direction Register (DDRA), $1A($3A) and the Port A Input Pins
(PINA) $19($39). The Port A Input Pins address is read only, while the Data Register and the
Data Direction Register are read/write.
All port pins have individually selectable pull-up resistors. When pins PA0 to PA7 are used as
inputs and are externally pulled low, they will source current if the internal pull-up resistors are
activated.
Port A Data Register – PORTA
Bit
7
6
5
$1B ($3B) PORTA7 PORTA6 PORTA5
Read/Write
R/W
R/W
R/W
Initial Value
0
0
0
4
PORTA4
R/W
0
3
PORTA3
R/W
0
2
PORTA2
R/W
0
1
PORTA1
R/W
0
0
PORTA0
R/W
0
PORTA
Port A Data Direction Register – DDRA
Bit
7
6
5
4
$1A ($3A)
DDA7
DDA6
DDA5
DDA4
Read/Write
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
3
DDA3
R/W
0
2
DDA2
R/W
0
1
DDA1
R/W
0
0
DDA0
R/W
0
DDRA
54 AT43USB353M
3307B–USB–4/04